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bcm2835-dma: Add support for per-channel flags

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Add the ability to interpret the high bits of the dreq specifier as
flags to be included in the DMA_CS register. The motivation for this
change is the ability to set the DISDEBUG flag for SD card transfers
to avoid corruption when using the VPU debugger.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
This commit is contained in:
Phil Elwell
2018-07-20 22:03:41 +01:00
committed by popcornmix
parent 3dd92c4782
commit 73a06eaf37
1 changed files with 8 additions and 2 deletions
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10
drivers/dma/bcm2835-dma.c
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@@ -132,6 +132,10 @@ struct bcm2835_desc {
#define BCM2835_DMA_S_DREQ BIT(10) /* enable SREQ for source */
#define BCM2835_DMA_S_IGNORE BIT(11) /* ignore source reads - read 0 */
#define BCM2835_DMA_BURST_LENGTH(x) ((x & 15) << 12)
#define BCM2835_DMA_CS_FLAGS(x) (x & (BCM2835_DMA_PRIORITY(15) | \
BCM2835_DMA_PANIC_PRIORITY(15) | \
BCM2835_DMA_WAIT_FOR_WRITES | \
BCM2835_DMA_DIS_DEBUG))
#define BCM2835_DMA_PER_MAP(x) ((x & 31) << 16) /* REQ source */
#define BCM2835_DMA_WAIT(x) ((x & 31) << 21) /* add DMA-wait cycles */
#define BCM2835_DMA_NO_WIDE_BURSTS BIT(26) /* no 2 beat write bursts */
@@ -445,7 +449,8 @@ static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
c->desc = d = to_bcm2835_dma_desc(&vd->tx);
writel(d->cb_list[0].paddr, c->chan_base + BCM2835_DMA_ADDR);
writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
writel(BCM2835_DMA_ACTIVE | BCM2835_DMA_CS_FLAGS(c->dreq),
c->chan_base + BCM2835_DMA_CS);
}
static irqreturn_t bcm2835_dma_callback(int irq, void *data)
@@ -472,7 +477,8 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
* if this IRQ handler is threaded.) If the channel is finished, it
* will remain idle despite the ACTIVE flag being set.
*/
writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE,
writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE |
BCM2835_DMA_CS_FLAGS(c->dreq),
c->chan_base + BCM2835_DMA_CS);
d = c->desc;